1. Field of the Invention
The invention relates to an apparatus for measurement of the thickness of thin layers by means of X-ray radiation.
2. Relevant Art
An apparatus of this generic type is known from DE 32 39 379 C2, which is used for measurement of the thickness of thin layers on the basis of the X-ray fluorescence principle. This apparatus has an X-ray tube which emits X-rays which are directed at a layer to be measured on a measurement object. An aperture apparatus is provided between the measurement object of [sic] the X-ray tube at a variable distance from the measurement object or from the layer to be measured, and limits the X-ray radiation to a measurement point on the layer to be measured. The florescence rays which are emitted from the irradiated measurement object are detected and evaluated by a detector. A semi-reflective deflection mirror is provided in the beam path between the aperture apparatus and the X-ray tube, allows the X-ray radiation to pass through, and allows a view of the measurement object and of the layer to be measured.
The aperture apparatus of this apparatus has two or more through-holes which are arranged at a fixed distance from one another and have different sizes. These through-holes can be chosen as appropriate for the measurement task, as a result of which it is possible to detect small measurement points or zones which can be defined exactly. This apparatus allows individual very small areas on the layer to be measured to be determined exactly. A high intensity is required for this purpose, and this acts on the measurement object. The longer the measurement time, the greater is the measurement precision which can be detected.
The measurement of the thickness of thin layers can also be carried out for mass-produced items. For example, in the case of valve parts for injection pumps, it is necessary to detect a layer thickness which has been applied by an electrochemical plating process. Millions of these parts are produced. The measurement process for determining the thickness of thin layers must take only a short measurement time.